Radiation shielding fabric



Feb. 7, 1961 w. w. DRUMMOND RADIATION SHIELDING FABRIC Filed March 23, 1955 INVENTOR. WARREN WE/VDELL DRUMMOND BY q A MM Attorney United States Patent ""cc RADIATION SHIELDING FABRIC Warren Wendell Drummond, Madison, Wis., assignor to Bjorksten Research Laboratories, Inc., Madison, Wis., a corporation of Illinois Filed Mar. 23, 1955, Ser. No. 496,228

4 Claims. (Cl. 250-408) This invention relates to flexible radiation shields, and more particularly to fabricor mat-like structures.

Heretofore, lead glass fibers have been employed for shielding, as have lead plates. However, lead glass is expensive, and is not very eflicient; while lead coated fabric or plates are too inflexible for convenient use where flexibility is desirable.

An object of this invention is a radiation shielding material of moderate cost and high flexibility and strength.

Another object is a method for manufacturing such shielding material.

Further objects will become apparent as the following detailed description proceeds.

In accordance with my invention, I apply a coating of a dense low melting material, such as lead, tin, bismuth, indium and the like, and alloys thereof, to glass fibers as these are being formed, then I randomize the fiber using any of the means known to the art, such as blowing chopped fiber, suspending chopped fiber and deposition of it on a felt; or by winding the continuous filaments in a random mat like arrangement.

In any of these randomizing processes, a mat-like structure will result; however, this structure is too loose and mechanically weak for the purposes intended.

To strengthen, compact and stabilize the structure, I expose it to heat slightly below the melting pointof the coating metal, and to pressure, so that the fibers are fused together by the coating metal, to form a compact mat of high density and strength. The metal coating prevents the abrasion, which would otherwise limit the wear characteristics of the metal fiber.

The invention is further illustrated by the figure which is a longitudinal diagrammatic view of the process and the article produced thereby, wherein metal coated vitreous fiber may be prepared with a coating by any of the metallizing means known to the art. Randomizing means 2 may consist of chopping rolls 2 and 2" adapted to chop the fiber into small lengths. In any event, the fiber coated with heavy, low melting metal is spread out in a random, felt like arrangement on a conveying means 3. The loose mat thus produced is passed on to a heat- 2,971,095 Patented Feb. 7, 1961 ing means such as oven 4, and then, while still hot, is passed between pressure means such as calendar rolls 5, in order to press together the heated fibers, so as to cause the metal to fuse together, after which the fabric is wound upon mandrel 6. For heating I prefer to employ temperatures moderately below the melting point of the metal or alloy employed; I may even use temperature slightly above the melting point of the metal, but in no case may the temperature be allowed to increase to the point where the coating begins to flow off the fibers.

It is sometimes advantageous to use an inert or reducing atmosphere; however, generally this is not necessary. I prefer to use lead, or alloys preponderantly based on lead for the coating material according to the invention, but I may also use tin, bismuth, antimony, indium and the like and the alloys of such metals.

The resultant mat is particularly useful for the preparation of radiation protective shields, clothing and flexible laboratory shielding.

It is thus seen that the invention is broad in scope, and is not to be restricted excepting by the claims, in which it is my intention to include all novelty inherent in this invention as broadly as possible in view of prior art.

Having thus disclosed my invention, I claim:

1. As an article of manufacture, a mat composed of ceramic fibers coated with lead, said fibers having a random arrangement, said fibers being bonded together by fusion of the said lead coating substantially only at the points of contact, said article being flexible.

2. As an article of manufacture, a mat composed of glass fibers coated with a low melting heavy metal composition, said fibers being bonded together by fusion of the said low melting metal composition substantially only at the points of contact, said article being flexible.

3. As an article of manufacture, a mat composed of ceramic fibers coated with a low melting high density metal selected from the group consisting of lead, tin, indium, bismuth, antimony and their alloys, said fibers being bonded together by fusion of said metal coatings substantially only at points of contact between individual fibers, said article being flexible.

4. As an article of manufacture, a mat composed of lead glass fibers coated with a low melting, high density metal, said fibers being bonded together by fusion of said metal coatings substantially only at points of contact between individual fibers, said article being flexible.

References Cited in the file of this patent UNITED STATES PATENTS 2,162,178 Marasco et a1. June 13, 1939 2,528,235 Loritsch Oct. 31, 1950 2,610,957 Steinman et al Sept. 16, 1952 2,679,609 Meloy May 25, 1954 2,794,128 Shasky May 28, 1957 

2. AS AN ARTICLE OF MANUFACTURE, A MAT COMPOSED OF GLASS FIBERS COATED WITH A LOW MELTING HEAVY METAL COMPOSITION, SAID FIBERS BONDED TOGETHER BY FUSION OF THE SAID LOW MELTING METAL COMPOSITION SUBSTANTIALLY ONLY AT THE POINTS OF CONTACT, SAID ARTICLE BEING FLEXIBLE. 